Well bore scratcher



Jan. 30, 1962 F. M. GIST 3,018,831

WELL BORE SCRATCHER Filed July 21, 1958 2 Sheets-Sheet 1 INVENTOR Fred Morgan Gisl ATTORNEYS Jan. 30, 1962 F.IM. GIST 3,018,831

WELL BORE SCRATCHER Filed July 21, 1958 2 Sheets-Sheet 2 Fig. 8

46 INVENTOR Fred Morgan 6752 ATTORNEYS United States Patent Ofiice 3,018,831 Patented Jan. 30, 1962 3,018,831 WELL BORE SCRATCHER Fred Morgan Gist, 103 V & J Tower, Midland, Tex. Filed July 21, 1953, Ser. No. 749,705 9 Claims. (Cl. 166-173) This invention relates to new and useful improvements in well bore scratchers.

One object of the invention is to provide an improved well bore scratcher for mounting on a well pipe or casing to clean the wall of a well bore by reciprocation and/or rotation of the well pipe prior to cementing so as to obtain a more positive bond between the cement and well bore wall.

An important object of the invention is to provide an improved well bore scratcher having resilient wall-engaging elements pivotally connected to a collar for mounting on a well pipe whereby the elements may undergo movement relative to the collar as well as deformation so as to permit the pasage of said elements through a close well bore or other opening without permanently distorting said elements.

A particular object of the invention is to provide an improved well bore scratcher, of the character described, wherein the resilient wall-engaging elements are coiled in substantially circular loops extending laterally outward of the collar and having free end portions for bearing against said collar to urge elongated curved portions of said elements into flexible engagement with the wall of the well bore for more thoroughly cleaning the wall.

Another object of the invention is to provide an improved well bore scratcher, of the character described, wherein the collar may be slidably confined on the well pipe or fixed thereto and wherein each well-engaging element has relatively loose pivotal connection with the collar for pivoting about an axis parallel to the longitudinal axis of the well pipe whereby the elements may undergo appreciable movement relative to said collar and have greater flexibility.

A construction designed to carry out the invention will be hereinafter described, together with other features of the invention.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings, wherein examples of the invention are shown, and whereini FIG. 1 is a side elevational view of a well scratcher, constructed in accordance with the invention, mounted on a well pipe,

FIG. 2 is a horizontal, cross-sectional view, taken on the line 2-2 of FIG. 1, showing the scratcher in plan,

FIG. 3 is a view, similar to FIG. 2, showing the scratcher in a well bore with its resilient elements deformed,

FIG. 4 is an enlarged, side elevational view showing the mounting of one of the elements.

FIG. 5 is a horizontal, cross-sectional view, taken on the line 5-5 of FIG. 4,

FIG. 6 is an enlarged plan view of a modified scratcher mounted on a well pipe, shown in cross-section,

FIG. 7 is a side elevational view of the joint of the collar of the modified scratcher,

FIG. 8 is an enlarged, horizontal, cross-sectional view, taken on the line 8-8 of FIG. 7, and

FIG. 9 is an enlarged, sideelevational view of one of the serrated portions of the collar for embedding in the well pipe.

In the drawings, the numeral 10 designates a well bore scratcher embodying the principles of the invention and mounted on a conventional well casing or pipe 1 1. The

scratcher includes a support 12, in the form of an annular band or collar, having a plurality of resilient, wallengaging elements or scratching fingers 13 pivotally connected thereto in spaced relation to one another. Although the collar 12 may be welded or otherwise secured to the casing 11, said collar is shown slidably confined on said casing between suitable stops, such as the couplings 14 which connect the casing sections (FIG. 1). Of course, when slidably confined, the collar is freely rotatable relative to the casing. It is noted that any desired number of scratchers may be mounted on the casing and that some of said scratchers may be slidably confined thereon while others may be secured to said casing.

As disclosed in my co-pending application, Serial No. 569,569, filed March 5, 1956, now Patent No. 2,868,299, each resilient, wall-engaging element or finger 13 is formed of suitable spring wire of relatively small gauge and arranged in spaced pairs as shown in FIGS. l-3. Each pair of resilient fingers is formed of a single 'elongated wire 15 having its medial portion coiled in a helix 16 and confined on an upright arm or pin 17 carried by and extending axially of the collar 12. As shown most clearly in FIGS. 4 and 5, the pins 17 are made integral with the collar and are cut therefrom by recessing the collar to provide openings 18 therein. Each opening 18 is rectangular or substantially square with the pin projecting upwardly from the medial portion of its lower margin in parallel relation to the collar. The lower portion of each pin is offset radially outward, as shown at 19, whereby said pin is disposed radially outward of its opening 18 to prevent binding engagement of the helix 16 with the casing when the collar is mounted on said casing. For the latter purpose, the diameter of the helix exceeds the greatest transverse dimension of the pin and the opening is relatively wide, being approximately three times the width of said pin. The pins are bent outwardly from the collar to receive the helices and are then bent inwardly to confine said helices thereon. It is noted that the pins have their upper ends in close proximity to the upper margins of the openings whereby the space therebetween is less than the diameter of the wire 15.

Each element or finger 13 is in the form of a substantially circular loop 20 which extends laterally outward of the collar 12 and which is formed by coiling the end portions of the wire 15. The ends of the fingers or their loops 20 are free and unattached and terminate adjacent the collar for bearing thereagainst so as to urge the medial portions of the loops outwardly into engagement with the wall of a well bore 21 as shown in FIG. 3. The fingers are coiled in the same direction and the loops 20 of each pair are spaced from each other. It is pointed out that the free ends of the fingers or their loops permit deformation and limited movement of said fingers relative to the collar when the casing 11 is rotated or reciprocated. Also the free ends prevent the fingers from hanging on obstructions and being damaged.

A modified casing scratcher 40 is shown in FIGS. 6 through 9 and includes an annular band or collar 41 for supporting the resilient, wall-engaging elements or scratching fingers 13. The collar 41 includes a plurality of outwardly ofiiset pins 42 disposed in openings 43, which are substantially identical to the pins 17 and opening 18, for receiving the helices 16 of the fingers to pivotally support the same (FIGS. 7 and 8). As shown by the numeral 44, the collar 41 is split and has overlapping end portions adapted to be fastened by a wedge element or key 45 for clamping said collar in engagement with the casing. A pair of diametrically-opposed, serrated or toothed portions 46 are formed on the inner surface of the collar for embedding in the exterior of the casing so as to positively grip said casing and prevent relative movement of said collar. A U-shaped bracket 47 projects from one of the end portions of the collar for supporting one of the fingers 13 adjacent the joint 44 of said collar.

The well bore scratchers and 40 function in substantially the same manner and are adapted to scrape and remove the drilling mud which coats the wall of the well bore prior to cementing in order to obtain a more positive bond between the cement and the bore wall. The flexibility of the fingers is enhanced by the loose pivotal connection of their helices 16 to the pins 17 and 42 as well as the bracket 47. Although the fingers overlap, the same are spaced from one another sufiiciently to provide flow paths therebetween and prevent accumulation of material dislodged or removed by said fingers, which material may include some loose formation, as well as facilitate the carrying oif of said material by circulated fluid.

Due to the coiling of the resilient fingers in substantially circular loops, said fingers are more flexible and will more readily conform to the irregular contour of a well bore. A greater surficial contact between the fingers and the wall of the well bore is provided by the circular shape of said fingers whereby their arcuate medial portions engage the circular bore wall. As shown in FIG. 3, the smaller the annulus between the casing and well bore, the greater the surficial contact of the fingers. Since the fingers are formed of spring wire, the same may undergo considerable deformation without being permanently bent or distorted out of their desired shape. It is noted that the free end portions of the fingers are disposed adjacent and may bear against the collar 12 or 41 for urging the medial portions of said fingers into scraping contact with the bore wall. In addition to the loose pivotal mounting of the fingers, which permits the same to undergo appreciable movement relative to the collar and its pins, the flexibility of said fingers is increased by the upright disposition of their helices.

Since the substantially circular fingers are more flexible than straight scratching elements, there is less danger of damaging said fingers upon reversing the direction of movement of the casing. In addition to removing the undesirable mud cake from the bore wall so that a better bond is obtained between the cement and bore wall, the well bore scratchers of the present invention function to reinforce the cement. It is pointed out that the free ends of the fingers, their loose pivotal mounting and their circular shape coact to provide increased flexibility without sacrificing the strength of said fingers.

The foregoing description of the invention is explanatory thereof and various changes in the size, shape and materials, as well as in the details of the illustrated con- 'struction may be made, within the scope of the appended claims, without departing from the spirit of the invention.

What I claim and desire to secure by Letters Patent is:

l. A well bore scratcher including a collar for mounting on a well casing, a plurality of independent resilient fingers attached to the collar in spaced relation to one another, each finger having a portion coiled in a relatively small helix, and a plurality of upright pins on said collar for confining the helices to loosely pivot the fingers for movement relative to one another about axes substantially parallel to the longitudinal axis of the casing, each finger being coiled in a loop of relatively large diameter extending laterally outward of said collar and casing, and having a curved medial portion for engagement with the wall of a well bore, the loops of the fingers being spaced from one another to provide flow paths therebetween, each loop having a free end portion terminating adjacent said collar for bearing thereagainst to urge the medial portion of said loop into engagement with the wall of the well bore and for increasing the flexibility of the finger.

2. A well bore scratcher including a collar for mounting on a well casing, a plurality of independent pairs of resilient fingers attached to the collar in spaced relation to one another, each pair of fingers having a common portion therebetween coiled in a relatively small helix, and a plurality of upright pins on said collar for confining the helices to loosely pivot the pairs of fingers for movement relative to one another about axes substantially parallel to the longitudinal axis of the casing, each pair of fingers having end portions coiled to provide a pair of loops of relatively large diameter extending laterally outward of said collar and casing and having curved medial portions for engagement with the wall of a well bore, the loops of the fingers being spaced from one another to provide flow paths therebetween, each loop having a free end portion terminating adjacent said collar for bearing thereagainst to urge the medial portion of said loop into engagement with the wall of the well bore and for increasing the flexibility of the finger.

3. A well bore scratcher including an annular support for mounting on a well casing, a plurality of resilient fingers coiled in loops of relatively large diameter disposed around and extending laterally outward of the support and casing and having curved medial portions for engagement with the wall of a well bore, the loops of the fingers being spaced from one another to provide flow paths therebetween, and a plurality of upright means on the support pivotally connecting the inner portion of each of the fingers to said support for limited movement about axes sub stantially parallel to the longitudinal axis of the casing.

4. A well bore scratcher including an annular support for mounting on a well casing, a plurality of resilient fingers coiled in loops of relatively large diameter disposed around and extending laterally outward of the support and casing and having curved medial portions for engagement with the wall of a well bore, the loops of the fingers being spaced from one another to provide flow paths therebetween, each finger having a portion coiledin a relatively small helix, and upright means on said support for confining the helices to pivotally connect the fingers thereto.

5. A well bore scratcher as set forth in claim 4 wherein the support is in the form of a collar adapted to be slidably confined on the casing.

6. A well bore scratcher as set forth in claim 4 wherein the support is in the form of a collar adapted to be fixed to the casing.

7. A well bore scratcher including an annular support for mounting on a well casing, a plurality of resilient fingers coiled in loops of relatively large diameter disposed around and extending laterally outward of the support and casing and having curved medial portions for engagement with the wall of a well bore, the loops of the fingers being spaced from one another to provide flow paths therebetween, and means on said support pivotally connecting the inner portion of each of said fingers to said support to permit limited movement of said fingers relative thereto and to one another, the loop of each finger having a free end portion terminating adjacent said support for bearing thereagainst to urge the medial portion of said loop into engagement with the well bore wall and for increasing the flexibility of the finger.

8. A well bore scratcher including an annular support for mounting on a well casing, a plurality of resilient fingers coiled in loops of relatively large diameter disposed around and extending laterally outward of the support and casing and having curved medial portions for engagement with the wall of a well bore, the loops of the fingers being spaced from one another to provide fiow paths therebetween, and means on said support pivotally connecting the inner portion of each of said fingers to said support to permit limited movement of said fingers relative thereto and to one another, the fingers being formed in pairs having integral inner portions whereby each pair 3,018,881 5 of fingers has an intermediate common portion pivotally connected to said support and end portions coiled to provide said loops.

9. A well bore scratcher as set forth in claim 8 wherein 2298985 Sun et a1 1942 5 2,369,222 Every Feb. 13, the loops of each pan of fingers have free end portions 2 671 515 Hall Man terminating adjacent the support for bearing thereagainst 2:674:317 Kipper APR to urge the medial portions of said loops into engagement 2,685,931 Bakelet 1 Aug with the wall of the well bore and for increasing the fieXi- 2,802,536 Baker Aug. 13,

bility of the fingers.

References Cited in the file of this patent UNITED STATES PATENTS Wright et a1. Mar. 11, 

